You should be able to get a bolt stop for your pistol. Parts are around from the different parts suppliers.
There's 2 different styles IIRC. One for the early nylon stocked XP100 and one for the XP100R.

Some of the difference bolt stop parts require an FFL to purchase. I don't believe the earlier style XP100 bolt stop itself does as the pistol was introduced prior to the Mod 600 Carbine which shares the same action. The early style spring and/or pin may require one though.

Maybe they've done away with all that nonsense by now..